Air turbocompressor refrigeration systems



Oct. 26, 1965 DUBINSKY ETAL 3,213,640

AIR TURBOCOMPRESSOR REFRIGERATION SYSTEMS Filed April 19. 1963 6' INVENTORS M 6'. .pUV/VSKY JMAM7 YJM ATTORNEYS United States Patent 3,213,640 AIR TURBOCOIWPRESSOR REFRIGERATION SYSTEMS Moisei Grigorievich Dubinsky, 2 Frunzenskaja 10, Apt. 46, and Sergei Konstantinovich Tumansky, Vosstanija Square I, Apt. 363, both of Moscow, U.S.S.R.

Filed Apr. 19, 1963, Ser. No, 274,898 2 Claims. (Cl. 62-402) This invention refers to a method of operation of air turbocompressor refrigerator installations with regenerators to obtain low temperatures of the order of -70 C. to 160 C.

It is known that air refrigerator installations appeared as far back as carbon dioxide and ammonia installations. However, as they are not economical, when not very low negative temperatures (down to -40 C.) are required, owing to the low efiiciency of compression and expansion, they were almost completely supplanted by steam refrigerator installations.

The introduction of regeneration into the air cycle of the process has considerably improved the thermodynamic performance of air refrigerator installations, especially in those cases where the refrigerator installation operates over a Wide range of limit temperatures.

In particular, air turbocompressor refrigerator installations are known where cooling is obtained as a result of expansion of atmospheric air in a turboexpander rang ing from atmospheric pressure down to a lower pressure. In such installations, the atmospheric air passes through a precooled regenerator, deposits the atmospheric humid ity in the regenerator elements, cools down to a certain negative temperature (e.g. down to 50 C.), and then passes to the inlet of the turboexpander, where expansion of the air down to a lower pressure takes place, which results in further cooling.

After passing through the turboexpander, the air is directed into the refrigeration chamber, where its temperature is again raised (e.g. to 50 C.) by the heat removed from the objects to be refrigerated. After passing through the refrigeration chamber, the air is directed into the second regenerator, and passing through the latter it cools down the regenerator elements and absorbs the humidity previously deposited in the elements. From the second regenerator, the air passes into the compressor, where the air is compressed to atmospheric pressure, its temperature then rising and is ejected into the atmosphere. The regenerators are periodically changed over to ensure regenerative heat exchange.

The refrigerator installation operating as described above has no air dryer and no heat exchanger for heat transfer, generally used in refrigerating machines, as, after passing through the compressor the heated air is ejected into the atmosphere (provided the same is not required from some other purpose).

The disadvantage of such a method of operation of an air turbocompressor refrigerator installation lies in the fact that a vacuum must be produced in the refrigeration chamber, which introduces difiiculties in designing large capacity refrigeration chambers.

If, on the other hand, the refrigerator installation operates as described above with pressure, vacuum in the refrigeration chamber can be avoided, but in such case, to ensure heat transfer, a cumbersome heat exchanger, usually of the air-water type, would be required downstream from the compressor.

The aim of this invention is to eliminate the above difliculties in the operation of air turbocompressor refrigerator installations with regenerators, as the atmospheric air, after passing through one of the regenerators, is directed first into the refrigeration chamber, then into 3,213,640 Patented Oct. 26, 1965 the turbine, further into the second regenerator of the installation, and into the compressor, whence it is ejected into the atmosphere.

Such a method of operation of refrigerator installations requires no vacuum in the refrigeration chamber, no dryers for atmospheric air, and no heat exchangers for transfer of heat from the cycle.

The aim of this invention is to provide a method of operation of air turbocompressor refrigerator installations Where atmospheric (or approximately atmospheric) pressure is retained in the refrigeration chamber. A further aim of this invention is to render possible more efiicient use of the refrigerator installation.

The invention is intended essentially, but not exclusively, for cooling various kinds of equipment for testing, also for freezing of foodstuffs, in particular for freezing of fish.

The method of operation proposed by the inventors can be used in installation having axial or centrifugal turbines and compressors, as well as in installations having reciprocating, propeller, or other mechanisms for air compression and expansion.

The regenerator used may be any regenerative heat exchanger.

FIG. 1 shows, as an example, the diagrammatic arrangement of an air turbocompressor refrigerator installation, making it possible to practice the proposed method of operation.

FIG. 2 shows the T-S diagram of operation of the installation by the proposed method.

The refrigerator installation comprises: a turboexpander 1, compressor 2, regenerative heat exchangers '3 and 4, refrigeration chamber 5, power transmission 6, valve chests 7 and 8 connected to the heat exchangers 3 and 4, valves 7' and 8' in the valve chests 7 and 8, and by-pass conduit 9.

The atmosperic air enters through an inlet 11 into the valve chest 7 and with the valve 7' in the full line position passes into heat exchanger 3, which has previously been cooled by means of the turboexpander 1; in

passing through the heat exchanger 3 the air is cooled down and deposits its humidity in the elements of the heat exchanger 3; then, through the valve chest 8 with the valve 3' in the full line position, the air passes through conduit 12 into the refrigeration chamber 5, where its temperature is raised due to cooling of the objects contained in the chamber. From the refrigeration chamher, the air passes through a conduit 13 into the turboexpander 1, where it expands (its temperature being lowered in consequence), the temperature rise of the air in the refrigeration chamber being equal, even under ideal conditions to its temperatumre drop in the turboexpander. The turboexpander operates on the pressure differential: pressure in the refrigeration chamber and pressure at the inlet to compressor 2. The air, cooled down in the turboexpander 1, passes through conduit 14 and the valve chest 8 to the other heat exchanger 4, and, in passing along the latter, it cools down the elements of the heat exchanger and absorbs the previously deposited humidity.

From heat exchanger 4 the air passes through valve chest 7, through conduit 15 and into the compressor 2, the pressure of the air being raised to atmospheric and, thus heated up, and is thereafter ejected from the compressor 2 into the atmosphere through conduit 10, provided the heat of this air is not required for some other purpose.

Periodically, changeover of the heat exchangers 3 and 4 takes place by movement of the valves 7 and 8' from the full line positions to the dotted line positions to ensure regenerative heat exchange operation and the continuous supply of cold air into the refrigeration chamber.

Power developed into the turboexpander 1 is transmitted to the drive of compressor 2 by shaft 16 and additional power for driving the compressor 2 is supplied from an outside source through the power transmission 6 having a power input coupling 7.

During the starting period, when the refrigerating capacity of the machine is used to cool the constructional elements of the machine itself, the refrigeration chamber is cut off, and the air from heat exchanger 3 passes through the conduit 12 and by-pass conduit 9 to the conduit 13 and directly into turboexpander 1. The by-pass conduit 9 controlled by valves 18 and 19 permits rapid attainment of the temperature level required at the inlet to the refrigeration chamber.

Also, in regular service, the by -pass conduit 9 permits regulation of the operation of the turbocompressor depending on the heat load in the refrigeration chamber.

For regulation of the pressure in the refrigeration chamber and, in particular for compensation of hydraulic losses in the path between the inlet to the machine and the refrigeration chamber, an additional fan may be installed, if required, ahead of valve chest 7, or ahead 'of refrigeration chamber 5.

FIG. 2 is a T-S diagram showing the cycle, corresponding to operation of the installation in accordance with the proposed method of obtaining cold air.

As can be seen from FIG. 2, the process of cooling the -air in one heat exchanger corresponds to section a-b of the diagram. Section bc corresponds to heating of the air in the refrigeration chamber in the process of cooling the various objects. Section c-d corresponds to expansion of the air in the turboexpander. Section d-e of the cycle corresponds to heating of the air in the other heat exchanger in the process of cooling the element of the latter. Section e-g corresponds to compression of the air in the compressor. At point g, ejection of the hot air into the atmosphere takes place, and thus transfer of the heat from the cycle is accomplished.

In accordance with the preferred method of realization of the invention, one installation may be designed to the following specifications:

(1) Refrigerating capacity 26000 CaL/hour (2) Temperature at inlet to refrigeration chamber From 70 C. to

130 C. (3) Temperature rise of air in refrigeration chamber At:30 (4) Flow of air through installation 1 kg./sec.

(5) Power requirement N :55 to 70 kw.

It should be noted that this invention, owing to high efliciencies of the compressor and turbine, permits to obtain refrigeration at 80 C. or below at the inlet to the 4 refrigeration chamber with a higher refrigeration factor than in the case of existing two-stage steam refrigerating machines.

Although the invention has been described with reference to a preferred method of its realization, it is clear that modifications and alternatives are possible without deviating from the general idea and extent of the invention. Such modifications and alternatives are not to be considered as being outside the extent of the invention and of the subject matter of the patent.

What we claim is:

1. An air refrigeration system comprising a regenerative heat exchanger, 21 second regenerative heat exchanger, an air inlet from the atmosphere, valve means for selectively directing the flow of air from the atmosphere to one end of either said first or second heat exchanger, a refrigerating chamber, a conduit connecting the opposite ends of said first and second heat exchanger to said chamber, second valve means for selectively directing the flow of air to said chamber from either said first or second heat exchanger, a turboexpander, a second conduit connecting said chamber and the inlet of said expander, a by-pass conduit connecting said first and second conduit and valves for controlling the flow of air in said first and second conduits and said by-pass conduit, a third conduit connecting the outlet on said expander and said opposite ends of said first and second heat exchangers, said second valve means also serving to selectively direct flow of air from said expander to either said first or second heat exchanger, a compressor, a fourth conduit connecting the inlet of said compressor and said one end of said first and second heat exchangers, said first valve means also serving to selectively direct flow of air from said first or second heat exchanger to the inlet of said compressor and the outlet of said compressor being open to the atmosphere.

2. A system as defined in claim 1 in which drive means is provided between said turboexpander and said compressor, whereby at least a portion of the required power for driving said compressor is obtained from said expander and a power transmission coupled to said drive means and having means for coupling to an external power source to provide at least a portion of the power required for driving both said expander and said compressor.

References Cited by the Examiner UNITED STATES PATENTS 1,906,370 5/33 Darrow 62403 2,044,3 30 6/ 3 6 Richter 62403 2,175,162 10/39 Waterfill 62402 WILLIAM J. WYE, Primary Examiner.

ROBERT A. QLEARY, Examiner, 

1. AN AIR REFRIGERATION SYSTEM COMPRISING A REGENERATIVE HEAT EXCHANGER, A SECOND REGENERATIVE HEAT EXCHANGER, AN AIR INLET FROM THE ATMOSPHERE, VALVE MEANS FOR SELECTIVELY DIRECTING THE FLOW OF AIR FROM THE ATMOSPHERE TO ONE END OF EITHER SAID FIRST OR SECOND HEAT EXCHANGER, A REFRIGERATING CHAMBER, C ONDUIT CONNECTING THE OPPOSITE ENDS OF SAID FIRST AND SECOND HEAT EXCHANGER TO SAID CHAMBER, SECOND VALVE MEANS FOR SELECTIVELY DIRECTING THE FLOW OF AIR TO SAID CHAMBER FROM EITHER SAID FIRST OR SECOND HEAT EXCHANGER, A TURBOEXPANDER, A SECOND CONDUIT CONNECTING SAID CHAMBER AND THE INLET OF SAID EXPANDER, A BY-PASS CONDUIT CONNECTING SAID FIRST AND SECOND CONDUIT AND VALVES FOR CONTROLLING THE FLOW OF AIR IN SAID FIRST AND SECOND CONDUITS AND SAID BY-PASS CONDUIT, A THIRD CONDUIT CONNECTING THE OUTLET ON SAID EXPANDER AND SAID OPPOSITE ENDS OF SAID FIRST AND SECOND HEAT EXCHANGERS, SAID SECOND VALVE MEANS ALSO SERVING TO 